Frenzied Shrine

From Diablo Wiki

The Frenzied Shrine provides a powerful combat boost by adding a 25% bonus to Attack Speed for 2 minutes.

During beta testing this shrine boosted Critical Hit Damage by 25% as well, but that bonus was deemed too powerful and the bonus was limited to Attack Speed for the game's release.

The Attack Rate boost is powerful on its own, and this shrine can be useful as a sort of equipment upgrade preview, since 25% is roughly the AS boost provided by 3 pieces of equipment boosting Attack Speed. (Many of which provide +8-9% Attack Speed.)

Shrines in Diablo III

Shrines are randomly-located, randomly-spawned objects that characters can click to receive temporary buffs. Shrine effects pass to all players in the area when they are first triggered. All shrine benefits last for 2 minutes, and characters can benefit from multiple different shrines at once. Shrine bonuses and durations do not stack, and hitting a second shrine of the same type will simply reset the time to the full two minute duration.